Walk suggestions around Darwin/Katherine

I will be walking the Jatbula trail at the end of the month and have given myself a week to check out some other national parks and acclimatise before I start the trail.
Can anyone suggest other walks, either day walks or overnighters that I should check out before I start? The hire car is not a 4wd so I would be limited to areas not that far off the beaten track.
Cheers
Can anyone suggest other walks, either day walks or overnighters that I should check out before I start? The hire car is not a 4wd so I would be limited to areas not that far off the beaten track.
Cheers